310 research outputs found

    Insights into the 1968–1997 Dasht-e-Bayaz and Zirkuh earthquake sequences, eastern Iran, from calibrated relocations, InSAR and high-resolution satellite imagery

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    The sequence of seismicity in the Dasht-e-Bayaz and Zirkuh region of northeastern Iran, which includes 11 destructive earthquakes within a period of only 30 years, forms one of the most outstanding examples of clustered large and intermediate-magnitude seismic activity in the world.We perform a multiple-event relocation analysis, with procedures to remove systematic location bias, of 169 earthquakes, most of which occurred in the period 1968–2008, to better image the distribution of seismicity within this highly active part of Iran. The geographic locations of the clustered earthquakes were calibrated by the inclusion of phase arrivals from seismic stations at short epicentral distances, and also by matching the relative locations of the three largest events in the study to their mapped surface ruptures. The two independent calibration methods provide similar results that increase our confidence in the accuracy of the distribution of relocated epicentres. These calibrated epicentres, combined with the mapping of faults from high-resolution satellite imagery, and from an InSAR-derived constraint on fault location in one case, allow us to associate individual events with specific faults, and even with specific segments of faults, to better understand the nature of the active tectonics in this region during the past four decades. Several previous assumptions about the seismicity in this region are confirmed: (1) that the 1968 August 30 Mw 7.1 Dasht-e-Bayaz earthquake nucleated at a prominent segment boundary and left-step in the fault trace, (2) that the 1968 September 11 Mw 5.6 aftershock occurred on the Dasht-e-Bayaz fault at the eastern end of the 1968 rupture and (3) that the 1976 November 7 Mw 6.0 Qayen earthquake probably occurred on the E–W left-lateral Avash Fault. We show, in addition, that several significant events, including the 1968 September 1 and 4 (Mw 6.3 and 5.5) Ferdows earthquakes, the 1979 January 16 (Mw 6.5) and 1997 June 25 (Mw 5.9) Boznabad events and the 1979 December 7 (Mw 5.9) Kalat-e-Shur earthquake are likely to have ruptured previously unknown faults. Our improved description of the faulting involved in the 1968–1997 earthquake sequence highlights the importance of rupturing of conjugate left- and right-lateral faults in closely spaced events, or potentially even within a single earthquake, as was likely the case at the eastern end of the 1979 November 27 (Mw 7.1) Khuli-Buniabad main shock. The high level of clustered seismic activity probably results from the simultaneous activity on left- and right-lateral faults, an inherently unstable arrangement that must evolve rapidly. The combination of high-resolution satellite imagery and calibrated earthquake locations is a useful tool for investigating active tectonics, even in the absence of detailed field observations

    Barycentric decomposition of quantum measurements in finite dimensions

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    We analyze the convex structure of the set of positive operator valued measures (POVMs) representing quantum measurements on a given finite dimensional quantum system, with outcomes in a given locally compact Hausdorff space. The extreme points of the convex set are operator valued measures concentrated on a finite set of k \le d^2 points of the outcome space, d< \infty being the dimension of the Hilbert space. We prove that for second countable outcome spaces any POVM admits a Choquet representation as the barycenter of the set of extreme points with respect to a suitable probability measure. In the general case, Krein-Milman theorem is invoked to represent POVMs as barycenters of a certain set of POVMs concentrated on k \le d^2 points of the outcome space.Comment: !5 pages, no figure

    Master Stability Functions for Coupled Near-Identical Dynamical Systems

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    We derive a master stability function (MSF) for synchronization in networks of coupled dynamical systems with small but arbitrary parametric variations. Analogous to the MSF for identical systems, our generalized MSF simultaneously solves the linear stability problem for near-synchronous states (NSS) for all possible connectivity structures. We also derive a general sufficient condition for stable near-synchronization and show that the synchronization error scales linearly with the magnitude of parameter variations.Our analysis underlines significant roles played by the Laplacian eigenvectors in the study of network synchronization of near-identical systems.Comment: 11 pages, 2 figure

    Epistemic and Ontic Quantum Realities

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    Quantum theory has provoked intense discussions about its interpretation since its pioneer days. One of the few scientists who have been continuously engaged in this development from both physical and philosophical perspectives is Carl Friedrich von Weizsaecker. The questions he posed were and are inspiring for many, including the authors of this contribution. Weizsaecker developed Bohr's view of quantum theory as a theory of knowledge. We show that such an epistemic perspective can be consistently complemented by Einstein's ontically oriented position

    Nanohertz Frequency Determination for the Gravity Probe B HF SQUID Signal

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    In this paper, we present a method to measure the frequency and the frequency change rate of a digital signal. This method consists of three consecutive algorithms: frequency interpolation, phase differencing, and a third algorithm specifically designed and tested by the authors. The succession of these three algorithms allowed a 5 parts in 10^10 resolution in frequency determination. The algorithm developed by the authors can be applied to a sampled scalar signal such that a model linking the harmonics of its main frequency to the underlying physical phenomenon is available. This method was developed in the framework of the Gravity Probe B (GP-B) mission. It was applied to the High Frequency (HF) component of GP-B's Superconducting QUantum Interference Device (SQUID) signal, whose main frequency fz is close to the spin frequency of the gyroscopes used in the experiment. A 30 nHz resolution in signal frequency and a 0.1 pHz/sec resolution in its decay rate were achieved out of a succession of 1.86 second-long stretches of signal sampled at 2200 Hz. This paper describes the underlying theory of the frequency measurement method as well as its application to GP-B's HF science signal.Comment: The following article has been submitted to Review of Scientific Instruments. After it is published, it will be found at (http://rsi.aip.org/

    Bohrification of operator algebras and quantum logic

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    Following Birkhoff and von Neumann, quantum logic has traditionally been based on the lattice of closed linear subspaces of some Hilbert space, or, more generally, on the lattice of projections in a von Neumann algebra A. Unfortunately, the logical interpretation of these lattices is impaired by their nondistributivity and by various other problems. We show that a possible resolution of these difficulties, suggested by the ideas of Bohr, emerges if instead of single projections one considers elementary propositions to be families of projections indexed by a partially ordered set C(A) of appropriate commutative subalgebras of A. In fact, to achieve both maximal generality and ease of use within topos theory, we assume that A is a so-called Rickart C*-algebra and that C(A) consists of all unital commutative Rickart C*-subalgebras of A. Such families of projections form a Heyting algebra in a natural way, so that the associated propositional logic is intuitionistic: distributivity is recovered at the expense of the law of the excluded middle. Subsequently, generalizing an earlier computation for n-by-n matrices, we prove that the Heyting algebra thus associated to A arises as a basis for the internal Gelfand spectrum (in the sense of Banaschewski-Mulvey) of the "Bohrification" of A, which is a commutative Rickart C*-algebra in the topos of functors from C(A) to the category of sets. We explain the relationship of this construction to partial Boolean algebras and Bruns-Lakser completions. Finally, we establish a connection between probability measure on the lattice of projections on a Hilbert space H and probability valuations on the internal Gelfand spectrum of A for A = B(H).Comment: 31 page

    Corresponding States of Structural Glass Formers

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    The variation with respect to temperature T of transport properties of 58 fragile structural glass forming liquids (68 data sets in total) are analyzed and shown to exhibit a remarkable degree of universality. In particular, super-Arrhenius behaviors of all super-cooled liquids appear to collapse to one parabola for which there is no singular behavior at any finite temperature. This behavior is bounded by an onset temperature To above which liquid transport has a much weaker temperature dependence. A similar collapse is also demonstrated, over the smaller available range, for existing numerical simulation data.Comment: 6 pages, 2 figures. Updated References, Table Values, Submitted for Publicatio

    Art therapy for Parkinson's disease.

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    Abstract Objective To explore the potential rehabilitative effect of art therapy and its underlying mechanisms in Parkinson's disease (PD). Methods Observational study of eighteen patients with PD, followed in a prospective, open-label, exploratory trial. Before and after twenty sessions of art therapy, PD patients were assessed with the UPDRS, Pegboard Test, Timed Up and Go Test (TUG), Beck Depression Inventory (BDI), Modified Fatigue Impact Scale and PROMIS-Self-Efficacy, Montreal Cognitive Assessment, Rey-Osterrieth Complex Figure Test (RCFT), Benton Visual Recognition Test (BVRT), Navon Test, Visual Search, and Stop Signal Task. Eye movements were recorded during the BVRT. Resting-state functional MRI (rs-fMRI) was also performed to assess functional connectivity (FC) changes within the dorsal attention (DAN), executive control (ECN), fronto-occipital (FOC), salience (SAL), primary and secondary visual (V1, V2) brain networks. We also tested fourteen age-matched healthy controls at baseline. Results At baseline, PD patients showed abnormal visual-cognitive functions and eye movements. Analyses of rs-fMRI showed increased functional connectivity within DAN and ECN in patients compared to controls. Following art therapy, performance improved on Navon test, eye tracking, and UPDRS scores. Rs-fMRI analysis revealed significantly increased FC levels in brain regions within V1 and V2 networks. Interpretation Art therapy improves overall visual-cognitive skills and visual exploration strategies as well as general motor function in patients with PD. The changes in brain connectivity highlight a functional reorganization of visual networks

    Recent progress in random metric theory and its applications to conditional risk measures

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    The purpose of this paper is to give a selective survey on recent progress in random metric theory and its applications to conditional risk measures. This paper includes eight sections. Section 1 is a longer introduction, which gives a brief introduction to random metric theory, risk measures and conditional risk measures. Section 2 gives the central framework in random metric theory, topological structures, important examples, the notions of a random conjugate space and the Hahn-Banach theorems for random linear functionals. Section 3 gives several important representation theorems for random conjugate spaces. Section 4 gives characterizations for a complete random normed module to be random reflexive. Section 5 gives hyperplane separation theorems currently available in random locally convex modules. Section 6 gives the theory of random duality with respect to the locally L0−L^{0}-convex topology and in particular a characterization for a locally L0−L^{0}-convex module to be L0−L^{0}-pre−-barreled. Section 7 gives some basic results on L0−L^{0}-convex analysis together with some applications to conditional risk measures. Finally, Section 8 is devoted to extensions of conditional convex risk measures, which shows that every representable L∞−L^{\infty}-type of conditional convex risk measure and every continuous Lp−L^{p}-type of convex conditional risk measure (1≤p<+∞1\leq p<+\infty) can be extended to an LF∞(E)−L^{\infty}_{\cal F}({\cal E})-type of σϵ,λ(LF∞(E),LF1(E))−\sigma_{\epsilon,\lambda}(L^{\infty}_{\cal F}({\cal E}), L^{1}_{\cal F}({\cal E}))-lower semicontinuous conditional convex risk measure and an LFp(E)−L^{p}_{\cal F}({\cal E})-type of Tϵ,λ−{\cal T}_{\epsilon,\lambda}-continuous conditional convex risk measure (1≤p<+∞1\leq p<+\infty), respectively.Comment: 37 page
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